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Volume 6 Issue 3

Jul.  1989

Article Contents

Medium-Range Oscillations in the Summer Tropical Easterlies at 200 hPa


doi: 10.1007/BF02661536

  • By the use of space-time spectral analysis and band-pass filter, some of the features of the medium-range Oscillations in the summer tropical easterlies (10oS-20o) at 200 hPa are investigated based on a two-year (1980 and 1982) wind (u, v) data set for the period from May to September. Space-time power spectral analysis shows that the total energy of the westward moving waves was the largest and that of the standing waves and eastward moving waves was relatively small in the 200 hPa easterlies; the total energy of the eastward moving waves was at minimum at 10oN. Three kind of the medium-range oscillations with about 50 day, 25 day and quasi-biweekly periods were found in the easterlies, which all show a remarkable interannual variation and latitudinal differences in these two years. The wave energy of zonal wind is mainly associated with the planetary waves (1-3), which all may make important contributions to the 50 day and 25 day oscillations in different years or different latitudes. The quasi-biweekly oscillation is mainly related to the synoptic waves (4-6). In equatorial region, the 50 day oscillation was dominant with a eastward phase propagation in 1982 while the dominant oscillation in 1980 was of 25day period with a westward phase propagations in 1980. Both of them are of the mode of zonal wavenumber 1. Strong westward 50 day oscillation was found in 10oN-20oN in these two years. Regular propagations of the meridional wind 50 day oscillation were also found in the easterlies.The 50 day and 25 day oscillation of zonal wind all demonstrate southward phase propagation over the region of the South Asia monsoon and northward phase propagation near interational date line, where are the climatic mean position of the tropical upper-tropospheric easterly jet and the tropical upper tropospheric trough (TUTT), respectively.
  • [1] Qiu Yongyan, Zhu Yafen, 1987: MEDIUM-RANGE OSCILLATIONS OF SYNOPTIC SYSTEMS IN SUMMER, ADVANCES IN ATMOSPHERIC SCIENCES, 4, 395-402.  doi: 10.1007/BF02656740
    [2] Lu Jingxi, Ding Yihui, 1989: Climatic Study on the Summer Tropical Easterly Jet at 200 hPa, ADVANCES IN ATMOSPHERIC SCIENCES, 6, 215-226.  doi: 10.1007/BF02658017
    [3] Chen Longxun, Jin Zuhui, 1984: THE MEDIUM-RANGE VARIATIONS OF THE SUMMER MONSOON CIRCULATION SYSTEM OVER EAST ASIA, ADVANCES IN ATMOSPHERIC SCIENCES, 1, 224-245.  doi: 10.1007/BF02678135
    [4] Chen Jiabin, A.J. Simmons, 1990: Sensitivity of Medium-Range Weather Forecasts to the Use of Reference Atmosphere, ADVANCES IN ATMOSPHERIC SCIENCES, 7, 275-293.  doi: 10.1007/BF03179761
    [5] Lu Longhua, Chen Xianji, Zhu Fukang, 1985: THE INTERANNUAL VARIATION OF MEDIUM-RANGE OSCILLATION CHARACTERISTICS IN THE UPPER TROPOSPHERE OVER THE SUBTROPICAL REGION, ADVANCES IN ATMOSPHERIC SCIENCES, 2, 54-62.  doi: 10.1007/BF03179737
    [6] Huang Boyin, Zhao Gaoxiang, Ji Liren, 1992: A Numerical Research on the Influences of the Diurnal Variation of Solar Radiation on the Medium-Range Weather Processes, ADVANCES IN ATMOSPHERIC SCIENCES, 9, 231-236.  doi: 10.1007/BF02657513
    [7] Zhang Qihe, Yu Shihua, 1990: Diagnosis of the Medium-Range Variation of the Subtropical High over the Western Pacific during a Meiyu Process by Three-Dimensional E-P Flux, ADVANCES IN ATMOSPHERIC SCIENCES, 7, 463-474.  doi: 10.1007/BF03342565
    [8] Swati Basu, K. J. Ramesh, Z. N. Begum, 1999: Medium Range Prediction of Summer Monsoon Activities over India vis-a-vis Their Correspondence with the Observational Features, ADVANCES IN ATMOSPHERIC SCIENCES, 16, 133-146.  doi: 10.1007/s00376-999-0009-0
    [9] Zhen HUANG, Shuanglin LI, Jianying LI, Chao ZHANG, 2023: Electronic Supplementary Materials to: The Combined Effects of the Tropical and Extratropical Quasi-biweekly Oscillations on the Record-setting Mei-yu Rainfall in the Summer of 2020*, ADVANCES IN ATMOSPHERIC SCIENCES.  doi: 10.1007/s00376-022-2050-1
    [10] Zhu Qiangen, Zhi Xiefei, 1988: MAINTENANCE AND OSCILLATION MECHANISMS OF SUM-MER TROPICAL UPPER-TROPOSPHERIC EASTERLIES, ADVANCES IN ATMOSPHERIC SCIENCES, 5, 127-140.  doi: 10.1007/BF02656775
    [11] CHEN Shumin, Youyu LU, LI Weibiao, WEN Zhiping, 2015: Identification and Analysis of High-Frequency Oscillations in the Eyewalls of Tropical Cyclones, ADVANCES IN ATMOSPHERIC SCIENCES, 32, 624-634.  doi: 10.1007/s00376-014-4063-x
    [12] Zhao Shengju, Zhou Chaodong, 1986: MODELS FOR MEDIUM- AND LONG-RANGE FORECAST-ING OF THE AMOUNT OF MIGRATION OF FIRST-GENERATION MOTHS INTO THE OUTBREAKING AREA OF THE SECOND- GENERATION ARMYWORM, ADVANCES IN ATMOSPHERIC SCIENCES, 3, 379-384.  doi: 10.1007/BF02678658
    [13] Fang Zongyi, 1985: THE PRELIMINARY SYUDY OF MEDIUM-SCALE CLOUD CLUSTERS OVER THE CHANGJIANG BASIN IN SUMMER, ADVANCES IN ATMOSPHERIC SCIENCES, 2, 334-340.  doi: 10.1007/BF02677249
    [14] S. V. Singh, S. R. Inamdar, R. H. Kripalani, K. D. Prasad, 1986: RELATIONSHIP BETWEEN 500 hPa RIDGE AXIS POSITIONS OVER THE INDIAN AND THE WEST PACIFIC REGIONS AND THE INDIAN SUMMER MONSOON RAINFALL, ADVANCES IN ATMOSPHERIC SCIENCES, 3, 349-359.  doi: 10.1007/BF02678655
    [15] Shumin CHEN, Weibiao LI, Zhiping WEN, Mingsen ZHOU, Youyu LU, Yu-Kun QIAN, Haoya LIU, Rong FANG, 2018: Variations in High-frequency Oscillations of Tropical Cyclones over the Western North Pacific, ADVANCES IN ATMOSPHERIC SCIENCES, 35, 423-434.  doi: 10.1007/s00376-017-7060-z
    [16] 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
    [17] LU Riyu*, DONG Huilin, SU Qin, and Hui DING, 2014: The 30-60-day Intraseasonal Oscillations over the Subtropical Western North Pacific during the Summer of 1998, ADVANCES IN ATMOSPHERIC SCIENCES, 31, 1-7.  doi: 10.1007/s00376-013-3019-x
    [18] Xiaohao QIN, Wansuo DUAN, Hui XU, 2020: Sensitivity to Tendency Perturbations of Tropical Cyclone Short-range Intensity Forecasts Generated by WRF, ADVANCES IN ATMOSPHERIC SCIENCES, 37, 291-306.  doi: 10.1007/s00376-019-9187-6
    [19] REN Baohua, HUANG Ronghui, 2003: 30-60-day Oscillations of Convection and Circulation Associated with the Thermal State of the Western Pacific Warm Pool during Boreal Summer, ADVANCES IN ATMOSPHERIC SCIENCES, 20, 781-793.  doi: 10.1007/BF02915403
    [20] Chen Yingyi, 1993: Predictability of the 500 hPa Height Field, ADVANCES IN ATMOSPHERIC SCIENCES, 10, 497-503.  doi: 10.1007/BF02656975

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Manuscript History

Manuscript received: 10 July 1989
Manuscript revised: 10 July 1989
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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Medium-Range Oscillations in the Summer Tropical Easterlies at 200 hPa

  • 1. National Research Center for Marine Environment Forecasts, State Oceanic Administration, Beijing 100081,Academy of Meteorological Science, State Meteorological Administration, Bejing 100081

Abstract: By the use of space-time spectral analysis and band-pass filter, some of the features of the medium-range Oscillations in the summer tropical easterlies (10oS-20o) at 200 hPa are investigated based on a two-year (1980 and 1982) wind (u, v) data set for the period from May to September. Space-time power spectral analysis shows that the total energy of the westward moving waves was the largest and that of the standing waves and eastward moving waves was relatively small in the 200 hPa easterlies; the total energy of the eastward moving waves was at minimum at 10oN. Three kind of the medium-range oscillations with about 50 day, 25 day and quasi-biweekly periods were found in the easterlies, which all show a remarkable interannual variation and latitudinal differences in these two years. The wave energy of zonal wind is mainly associated with the planetary waves (1-3), which all may make important contributions to the 50 day and 25 day oscillations in different years or different latitudes. The quasi-biweekly oscillation is mainly related to the synoptic waves (4-6). In equatorial region, the 50 day oscillation was dominant with a eastward phase propagation in 1982 while the dominant oscillation in 1980 was of 25day period with a westward phase propagations in 1980. Both of them are of the mode of zonal wavenumber 1. Strong westward 50 day oscillation was found in 10oN-20oN in these two years. Regular propagations of the meridional wind 50 day oscillation were also found in the easterlies.The 50 day and 25 day oscillation of zonal wind all demonstrate southward phase propagation over the region of the South Asia monsoon and northward phase propagation near interational date line, where are the climatic mean position of the tropical upper-tropospheric easterly jet and the tropical upper tropospheric trough (TUTT), respectively.

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