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1995 Fiscal Year Final Research Report Summary

Rol of the seasonal cycle and interseasonal variability on the interannual variability of the climate system.

Research Project

Project/Area Number 05452077
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field Meteorology/Physical oceanography/Hydrology
Research InstitutionUniversity of Tsukuba

Principal Investigator

YASUNARI Tetsuzo  Institute of Geoscience, The University of Tsukuba Professor, 地球科学系, 教授 (80115956)

Co-Investigator(Kenkyū-buntansha) TANAKA Hiroshi l.  Institute of Geoscience, The University of Tsukuba Assistang Professor, 地球科学系, 講師 (70236628)
Project Period (FY) 1993 – 1995
Keywordsmonsoon / Baiu / convective activities / land-sea interactions / general circulation / interseasonal variability / interannual variability / model experiment
Research Abstract

The convective activities at the tropical western Pacific is the major source of atmospheric energy which controls the global climate system. This study has investigated the role of the interseasonal variability, seasonal cycle, and interannual variability of the convective activities there upon the activities in Asian monsoon and the atmosphere-ocean interactions at the tropical Pacific.
The result of this study may be summarized as follows :
1) An abrupt shift of the active convection area in conjunction with the anomalous interseasonal variability is found. This jump is related to the onset of monsoonal circulation in Asia and the onset of Baiu in Japan.
2) The jump of the active convection area is related to the seasonal change of sea surface temperature and is controlled by the intensity of the convection activities through the land-sea interactions.
3) The interannual variability is resulted from the intensity of the unusual behavior of the interseasonal variability associated with the jump of the active convection area.
On the other hand, a simple barotropic model experiment is carried out to examine the cause of the interseasonal and interannual variabilities. The forced annual cycle is expected to excite its harmonics and subharmonics by the internal nonlinear dynamic modulationwhich tern out to be interseasonal and internnual variabilities. The results, however, show that the spectral features with and without the forced annual cycle are not altered by the inclusion of the annual cycle, except for the isolated spectral peak associated with the annual cycle forcing.
We suggest from the results of this numerical experiment that the harmonics and subharmonics, such as semiannual and biennial oscillations, are not excited by the nonlinear dynamic modulation of the forced annual cycle. Namely, the low-frequency variabilities, such as the semiannual and biennial oscillations, must be excited by the external forcing of the atmosphere rather than the internal dynamics.

  • Research Products

    (13 results)

All Other

All Publications (13 results)

  • [Publications] Yasunari, T., K. Ueno and T. Tomita: "Role of tropical/extropical interactions on the monsoon/atmosphere-ocear system MAOS) in the tropics." Proc. International conference on monsoon variubility and prediction. Trieste, Italy May 9-13. (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ueda, H., T.Yasunari and R. Kawamura: "Abrupt seasonal change of large-scale convective activity over the the Western Pacific in the northern summer." J. Meteor. Soc. Japan. 73. 795-809 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yasunari, T., T. Mito and M. Nishimori: "Two modes in the recent lower tropospheric warming in the northern hemisphere." Proc. Wadati Conference on Global Change and the Polar Climate, Tsukuba, Japan. 32-36 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tanaka, H. L. and K. Kimura: "Time spectral analysis for the natural variability of the barotropic model atmospher." WMO Weather Prediction Research Programmes.19. 218-220 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tanaka, H. L., K. Kimura: "Time spectral analysis for the natural variability of the barotropic model atmospher with annual cycle forcing." WMO Weather Prediction Research Programmes. 20. 7.70-7.72 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tanaka. H. L., R. Kanohgi and T. Yasunari: "Recent abnormal weather in the Arctic." Proc. Wadati Conference on Global Change and the Polar Climate, Tsukuba, Japan,. 13-16 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yasunari, T., K.Ueno and T.Tomita: "Role of tropical/extropical interactions on the monsoon/atmosphere-ocean system (MAOS) in the tropics" Proc.International conference on monsoon variability and predicition. Trieste, Italy. May 9-13. (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Ueda, H., T.Yasunari and R.Kawamura: "Abrupt seasonal change of large-scale convective activity over the Western Pacific in the northern summer" J.Meteor.Soc.Japan. 73. 795-809 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yasunari, T., T.Mito and M.Nishimori: "Two modes in the recent lower tropospheric warming in the northern hemisphere" Proc.Wadati Conference on Global Change and the Polar Climate, Tsukuba, Japan. 32-36 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Ueda, H.and T.Yasunari: "Maturing process of summer monsoon over the Western North Pacific-A coupled ocean/atmosphere system-" J.Meteor.Soc.Japan. 74 (to be accepted.).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tanaka, H.L., K.Kimura: "Time spectral analysis for the natural variability of the barotropic model atmosphere" WMO Weather Prediction Research Programs. No.19. 2.18-2.20 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tanaka, H.L., K.Kimura, and T.Yasunari: "Time spectral analysis for the natural variability of the barotropic model atmosphere with annual cycle forcing" WMO Weather Prediction Research Programs. No.20. 7.70-7.72 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Tanaka, H.L., R.Kanohgi, and T.Yasunari: "Recent abnormal weather in the Arctic" Proc.Wadati Conference on Global Change and the Polar Climate, Tsukuba, Japan. 13-16 (1995)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1997-03-04  

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